| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.pig; |
| |
| import java.io.IOException; |
| import java.lang.reflect.ParameterizedType; |
| import java.lang.reflect.Type; |
| import java.util.Deque; |
| import java.util.LinkedList; |
| import java.util.List; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PigLogger; |
| import org.apache.pig.backend.hadoop.executionengine.physicalLayer.PigProgressable; |
| import org.apache.pig.builtin.OutputSchema; |
| import org.apache.pig.classification.InterfaceAudience; |
| import org.apache.pig.classification.InterfaceStability; |
| import org.apache.pig.data.Tuple; |
| import org.apache.pig.impl.PigContext; |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.impl.logicalLayer.schema.Schema; |
| import org.apache.pig.impl.util.UDFContext; |
| import org.apache.pig.impl.util.Utils; |
| import org.apache.pig.parser.ParserException; |
| |
| |
| /** |
| * The class is used to implement functions to be applied to |
| * fields in a dataset. The function is applied to each Tuple in the set. |
| * The programmer should not make assumptions about state maintained |
| * between invocations of the exec() method since the Pig runtime |
| * will schedule and localize invocations based on information provided |
| * at runtime. The programmer also should not make assumptions about when or |
| * how many times the class will be instantiated, since it may be instantiated |
| * multiple times in both the front and back end. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Stable |
| public abstract class EvalFunc<T> { |
| /** |
| * Reporter to send heartbeats to Hadoop. If exec will take more than a |
| * a few seconds {@link PigProgressable#progress} should be called |
| * occasionally to avoid timeouts. Default Hadoop timeout is 600 seconds. |
| */ |
| protected PigProgressable reporter; |
| |
| /** |
| * Logging object. Log calls made on the front end will be sent to |
| * pig's log on the client. Log calls made on the backend will be |
| * sent to stdout and can be seen in the Hadoop logs. |
| */ |
| protected Log log = LogFactory.getLog(getClass()); |
| |
| /** |
| * Logger for aggregating warnings. Any warnings to be sent to the user |
| * should be logged to this via {@link PigLogger#warn}. |
| */ |
| protected PigLogger pigLogger; |
| |
| private static int nextSchemaId; // for assigning unique ids to UDF columns |
| protected String getSchemaName(String name, Schema input) { |
| String alias = name + "_"; |
| if (input!=null && input.getAliases().size() > 0){ |
| alias += input.getAliases().iterator().next() + "_"; |
| } |
| |
| alias += ++nextSchemaId; |
| return alias; |
| } |
| |
| /** |
| * Return type of this instance of EvalFunc. |
| */ |
| protected Type returnType; |
| |
| public EvalFunc(){ |
| |
| //Figure out what the return type is by following the object hierarchy upto the EvalFunc |
| |
| Class<?> superClass = getClass(); |
| Type superType = getClass(); |
| |
| Deque<Type> geneticsStack = new LinkedList<Type>(); |
| |
| // Go up the hierachy of the class up to the EvalFunc |
| while (!superClass.isAssignableFrom(EvalFunc.class)) |
| { |
| superType = superClass.getGenericSuperclass(); |
| superClass = superClass.getSuperclass(); |
| geneticsStack.push(superType); |
| } |
| |
| // From EvalFunc (superclass), go downward (subclass), |
| // find the first class materialize the genetics |
| Type materializedType = null; |
| while (!geneticsStack.isEmpty()) { |
| Type aType = geneticsStack.pop(); |
| if (aType instanceof ParameterizedType) { |
| // We materialized something, eg, materialized the type to Double, |
| // or materialized the type to Map<String, Object>, or materialized the type |
| // to T(another genetics). In the 1st case, getActualTypeArguments() |
| // returns a class, we can tell easily; In the 2nd and 3th case, |
| // getActualTypeArguments() returns a ParameterizedType, |
| // we cannot tell 2nd case from 3th case. |
| // So we need further check if the type inside materializedType |
| // are materialized (case 2) |
| materializedType = ((ParameterizedType)aType).getActualTypeArguments()[0]; |
| } |
| Type currentType = materializedType; |
| while (currentType instanceof ParameterizedType) |
| currentType = ((ParameterizedType)currentType).getActualTypeArguments()[0]; |
| if (currentType instanceof Class) { |
| returnType = materializedType; |
| break; |
| } |
| } |
| |
| String errMsg = getClass() + "extends the raw type EvalFunc. It should extend the parameterized type EvalFunc<T> instead."; |
| |
| if (returnType==null) |
| throw new RuntimeException(errMsg); |
| |
| //Type check the initial, intermediate, and final functions |
| if (this instanceof Algebraic){ |
| Algebraic a = (Algebraic)this; |
| |
| errMsg = "function of " + getClass().getName() + " is not of the expected type."; |
| if (getReturnTypeFromSpec(new FuncSpec(a.getInitial())) != Tuple.class) |
| throw new RuntimeException("Initial " + errMsg); |
| if (getReturnTypeFromSpec(new FuncSpec(a.getIntermed())) != Tuple.class) |
| throw new RuntimeException("Intermediate " + errMsg); |
| if (!getReturnTypeFromSpec(new FuncSpec(a.getFinal())).equals(returnType)) |
| throw new RuntimeException("Final " + errMsg); |
| } |
| |
| } |
| |
| |
| private Type getReturnTypeFromSpec(FuncSpec funcSpec){ |
| try{ |
| return ((EvalFunc<?>)PigContext.instantiateFuncFromSpec(funcSpec)).getReturnType(); |
| }catch (ClassCastException e){ |
| throw new RuntimeException(funcSpec + " does not specify an eval func", e); |
| } |
| } |
| |
| /** |
| * Get the Type that this EvalFunc returns. |
| * @return Type |
| */ |
| public Type getReturnType(){ |
| return returnType; |
| } |
| |
| // report that progress is being made (otherwise hadoop times out after 600 seconds working on one outer tuple) |
| /** |
| * Utility method to allow UDF to report progress. If exec will take more than a |
| * a few seconds {@link PigProgressable#progress} should be called |
| * occasionally to avoid timeouts. Default Hadoop timeout is 600 seconds. |
| */ |
| public final void progress() { |
| if (reporter != null) reporter.progress(); |
| else warn("No reporter object provided to UDF.", PigWarning.PROGRESS_REPORTER_NOT_PROVIDED); |
| } |
| |
| /** |
| * Issue a warning. Warning messages are aggregated and reported to |
| * the user. |
| * @param msg String message of the warning |
| * @param warningEnum type of warning |
| */ |
| public final void warn(String msg, Enum warningEnum) { |
| if(pigLogger != null) pigLogger.warn(this, msg, warningEnum); |
| else log.warn("No logger object provided to UDF: " + this.getClass().getName() + ". " + msg); |
| } |
| |
| /** |
| * Placeholder for cleanup to be performed at the end. User defined functions can override. |
| * Default implementation is a no-op. |
| */ |
| public void finish(){} |
| |
| |
| |
| /** |
| * This callback method must be implemented by all subclasses. This |
| * is the method that will be invoked on every Tuple of a given dataset. |
| * Since the dataset may be divided up in a variety of ways the programmer |
| * should not make assumptions about state that is maintained between |
| * invocations of this method. |
| * |
| * @param input the Tuple to be processed. |
| * @return result, of type T. |
| * @throws IOException |
| */ |
| abstract public T exec(Tuple input) throws IOException; |
| |
| /** |
| * Report the schema of the output of this UDF. Pig will make use of |
| * this in error checking, optimization, and planning. The schema |
| * of input data to this UDF is provided. |
| * <p> |
| * The default implementation interprets the {@link OutputSchema} annotation, |
| * if one is present. Otherwise, it returns <code>null</code> (no known output schema). |
| * |
| * @param input Schema of the input |
| * @return Schema of the output |
| */ |
| public Schema outputSchema(Schema input) { |
| OutputSchema schema = this.getClass().getAnnotation(OutputSchema.class); |
| try { |
| return (schema == null) ? null : Utils.getSchemaFromString(schema.value()); |
| } catch (ParserException e) { |
| throw new RuntimeException(e); |
| } |
| } |
| |
| /** |
| * This function should be overriden to return true for functions that return their values |
| * asynchronously. Currently pig never attempts to execute a function |
| * asynchronously. |
| * @return true if the function can be executed asynchronously. |
| */ |
| @Deprecated |
| public boolean isAsynchronous(){ |
| return false; |
| } |
| |
| |
| public PigProgressable getReporter() { |
| return reporter; |
| } |
| |
| |
| /** |
| * Set the reporter. Called by Pig to provide a reference of |
| * the reporter to the UDF. |
| * @param reporter Hadoop reporter |
| */ |
| public final void setReporter(PigProgressable reporter) { |
| this.reporter = reporter; |
| } |
| |
| /** |
| * Allow a UDF to specify type specific implementations of itself. For example, |
| * an implementation of arithmetic sum might have int and float implementations, |
| * since integer arithmetic performs much better than floating point arithmetic. Pig's |
| * typechecker will call this method and using the returned list plus the schema |
| * of the function's input data, decide which implementation of the UDF to use. |
| * @return A List containing FuncSpec objects representing the EvalFunc class |
| * which can handle the inputs corresponding to the schema in the objects. Each |
| * FuncSpec should be constructed with a schema that describes the input for that |
| * implementation. For example, the sum function above would return two elements in its |
| * list: |
| * <ol> |
| * <li>FuncSpec(this.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.DOUBLE))) |
| * <li>FuncSpec(IntSum.getClass().getName(), new Schema(new Schema.FieldSchema(null, DataType.INTEGER))) |
| * </ol> |
| * This would indicate that the main implementation is used for doubles, and the special |
| * implementation IntSum is used for ints. |
| */ |
| public List<FuncSpec> getArgToFuncMapping() throws FrontendException{ |
| return null; |
| } |
| |
| /** |
| * Allow a UDF to specify a list of files it would like placed in the distributed |
| * cache. These files will be put in the cache for every job the UDF is used in. |
| * The default implementation returns null. |
| * @return A list of files |
| */ |
| public List<String> getCacheFiles() { |
| return null; |
| } |
| |
| public PigLogger getPigLogger() { |
| return pigLogger; |
| } |
| |
| /** |
| * Set the PigLogger object. Called by Pig to provide a reference |
| * to the UDF. |
| * @param pigLogger PigLogger object. |
| */ |
| public final void setPigLogger(PigLogger pigLogger) { |
| this.pigLogger = pigLogger; |
| } |
| |
| public Log getLogger() { |
| return log; |
| } |
| |
| private Schema inputSchemaInternal=null; |
| /** |
| * This method will be called by Pig both in the front end and back end to |
| * pass a unique signature to the {@link EvalFunc}. The signature can be used |
| * to store into the {@link UDFContext} any information which the |
| * {@link EvalFunc} needs to store between various method invocations in the |
| * front end and back end. |
| * @param signature a unique signature to identify this EvalFunc |
| */ |
| public void setUDFContextSignature(String signature) { |
| } |
| |
| /** |
| * This method is for internal use. It is called by Pig core in both front-end |
| * and back-end to setup the right input schema for EvalFunc |
| */ |
| public void setInputSchema(Schema input){ |
| this.inputSchemaInternal=input; |
| } |
| |
| /** |
| * This method is intended to be called by the user in {@link EvalFunc} to get the input |
| * schema of the EvalFunc |
| */ |
| public Schema getInputSchema(){ |
| return this.inputSchemaInternal; |
| } |
| } |